Membrane Module Manifold with Integrated End Caps

ABSTRACT

Silicon carbide flat sheet filtration membranes are supported on one piece manifold/end cap structures. Ends of a large number of the parallel flat plate membranes are fitted into elongated end cap slots that are part of a single molded manifold/end cap structure, such a structure being at each end of the series of membranes. In addition, a one piece external frame module can be provided to receive the gang of flat plate membranes with attached manifold/end caps. In the event of a damaged plate, the plate can be removed and replaced along with a special end cap repair section. This provides advantages over prior arrangements with individual end caps for each module or potting of the flat plates into a box or chamber.

BACKGROUND OF THE INVENTION

This invention concerns membrane filtration, and particularly apparatusthat conducts post-filtration permeate water from flat plate ceramicmembranes.

The majority of silicon carbide (SiC) flat sheet suppliers use a flatsheet filter with end caps. These end caps (called end cap type herein)have O-rings and are inserted into a single permeate header. Thefiltered water travels from the outside of the SiC filter plate, throughchannels inside the plate, into the end caps and from there into apermeate header. One or two suppliers “pot” the flat plates into a boxor chamber (called potted type herein) on the end so that the watertravels directly into a void at the end.

The primary issue with the end cap type is the need for a lot of O-ringswhich can fail and are costly to produce and install. The primarybenefit is that the individual flat sheet membranes can be replacedindividually if damaged. The primary issue with the potted type is thatthe polyurethane that is used to “pot” the flat sheet membranes canswell and shrink significantly with temperature changes and in submergedapplications. With this expansion and contraction the brittle membraneflat sheets can be shattered. Additionally, by potting the plates anindividual sheet cannot be replaced.

The same type of sealant (polyurethane) typically is used in bothapplications and does not create an issue with the end cap type as theamount of sealant is very small so the impact is very small;additionally there is a little space between plates.

SUMMARY OF THE INVENTION

The invention resolves the above issues with a one piece, preferablyintegrally-molded manifold and end cap set. With the manifold/end capstructure of the invention the amount of required sealant issignificantly reduced and, importantly, O-rings are eliminated. In aprimary embodiment of the invention a damaged membrane plate can bereplaced; the replacement involves a type of patch to engage with themanifold. Although the one-piece integral design is preferable, themanifold/end cap structure could be formed in several pieces that areassembled together in sealed relationship.

In addition, the invention in one embodiment may include a one pieceexternal frame module that receives a full complement of membranes in anassembly retained by a manifold/end cap structure unit at each end. Theassembly, which can include, for example, 20 or 25 membranes, is loweredinto place such that the modular frame engages with the end cap/manifoldunits and helps provide rigid structural support for the membrane platesin service.

An important object of the invention is to eliminate O-rings in flatplate ceramic membrane assemblies while providing a unitary endcap/manifold structure that is efficiently attached to a series ofmembrane plates, allows replacement of individual membranes and isreliable and rugged in construction.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an assembly or cassette of a seriesof ceramic flat plate membranes, retained at both ends by a manifold/endcap unit of the invention.

FIG. 2 is a top plan view showing a manifold/end cap unit of theinvention.

FIG. 3 is a perspective view in greater detail illustrating theinvention.

FIG. 4 is a plan view showing the assembly of FIG. 1 and indicating abroken plate among the ceramic membrane plates.

FIG. 5 is a view similar to FIG. 4, showing a broken plate beingremoved.

FIG. 6 is a sectional elevation view indicating removal of a damagedmembrane plate with the aid of a cutting jig according to the invention.

FIG. 7 is a top plan view, enlarged for detail, showing the cutting jigengaged on the end cap/manifold.

FIG. 8 shows the cutting jig in perspective.

FIG. 9 is a perspective view showing a replacement plate end cap of theinvention.

FIG. 9A is a perspective view showing a repair coupling as analternative to the device shown in FIG. 9.

FIG. 10 is a perspective view showing an assembly or cassette of plates,retained by end caps/manifolds, and indicating removal and replacementof a broken plate, in three stages.

FIG. 11 is a perspective view showing an external frame module forreceiving the assembly plates as in FIG. 1.

FIG. 12 is a perspective view indicating stacking and ganging of plateassemblies retained in external frame modules.

DESCRIPTION OF PREFERRED EMBODIMENTS

In the drawings, FIG. 1 shows an assembly or cassette 10 of amultiplicity of flat plate ceramic filtration membranes 12 (e.g. about20 or 25 plates), retained together as a unit by end cap/manifolds 14,one at each end of the collection of plates. In some cases the platescould be capped off at one end, so that the end cap/manifold structureis only connected to receive permeate liquid from plates at one end ofthe plates, the other ends being supported or retained in a suitableway. Each plate has an end received in a slot of a manifold/end capstructure at each end.

FIG. 2 is a top view showing an end cap/manifold 14, and FIG. 3 alsoshows these end cap/manifolds 14 in better detail, engaged with themembranes. Each manifold/end cap structure 14 has a header 16 (sometimesreferred to as a header pipe), which is a permeate collection pipe, anda series of end caps 18 connected to and in communication with theinterior of the header 16. Each end cap is elongated, the full height ofthe membranes, defining a slot 20 that is sized to closely fit over andreceive the end of a membrane plate. The ends of the membrane plates 12are open and deliver permeate into the end cap, the end caps beingsecurely glued to the membrane plates using cements typically applied toconnect prior art end caps to ducts or pipes. As seen in the drawings,structure downstream of the end caps 18 narrows to a neck 22, extendingthe full height of the membrane plates and end caps, and which isconnected at top to the header pipe 16 for delivery of liquid into thatheader. Preferably the entire structure of the end cap/manifold unit 14is integrally molded as one piece, of an appropriate plastic materialsuch as Noryl, or a Nylon-ABS mix, or other strong plastics safe for theapplied environment which may be sewage treatment.

The narrow necks 22 on the end caps provide flexibility. The securementof the membrane plates with the end caps 18 stood away from the headerpipe 16 by the necks 22 enables some limited bending and flexing of theplates, and with the end caps connected for liquid communication only attheir tops to the header pipe 16 the plates are securely held but withsome flexing permitted, avoiding damage. The end caps 18 may also beconnected together at bottoms or elsewhere to add rigidity. As anexample, if a manifold/end cap structure is dimensioned as in FIG. 7,the necks have a width of about 7 mm and may stand out from the verticaltangent of the header pipe by about 4-5 mm. The drawings, includingFIGS. 1, 2 and 3, show exit ducts 24 on each end cap/manifold 14. Theseare for connection to conduits or pipes for removal of the permeate,usually from a series of assemblies. As illustrated, these exit ductshave provision for several large O-rings (not shown) for watertightconnections. The end caps 18, however, do not involve O-rings, which inthe prior art comprise a multiplicity of smaller O-rings securing endcaps to pipes or permeate headers, with some of the O-rings oftenfailing.

FIG. 4 shows the assembly 10 in plan view, while FIG. 5 shows the sameassembly but with a broken membrane plate 26 being removed. FIGS. 5through 10 indicate the procedure for removal and replacement of abroken ceramic plate. In FIG. 6, which is a cross sectional view inelevation looking at one of the flat plate membranes 12, a jig 28 isshown engaged onto the manifold/end cap header 16. The jig 28 is alsoshown in FIGS. 7, 8 and 10. Note that the FIG. 6 view of the jig 28 isalso in cross section. FIG. 7 further illustrates the use of a jig, andFIG. 8 shows the jig itself. The cut line 30 of a hacksaw blade is alsoindicated in FIG. 6, with the jig providing guidance for cutting throughthe header 16 in order to receive a section of header. Two parallel cutsare made, as indicated in FIG. 10, so that a gap is cut out of theheader, the gap being sufficiently wide as to encompass the header atboth sides of the narrow neck 22 of an end cap, that neck being, in oneexample, about 7 mm in width. Once both headers 16 have been cut, asillustrated in FIG. 10, each header is thereby separated into twopieces, each retaining remaining membrane plates 12. The broken plate 26has been removed in FIG. 10, simply by lifting out that plate with itsattached end caps and short sections of header, one at each end.

The cuts through the header pipe can be made without a jig if desired;also, a grinder could be used rather than a blade.

FIG. 7 shows the end cap/manifold 14 in greater detail, with the cuttingjig 28 engaged. In this view the cuts have been made and the section ofheader/end cap removed. The drawing shows that the integral end caps ofthe end cap/manifold structure 14 are very close together, as close asmolding will permit, separated by a space of about 1 mm or less. Thesecould be joined in molding, but to better facilitate removal andreplacement of plates they preferably are separated or just minimallyconnected as mentioned above.

FIG. 10 shows a replacement plate 31, with a special end cap replacementsection 32 at each end. The end cap or end cap replacement section 32 isalso shown in FIG. 9, prior to being attached to a ceramic plate.

FIG. 10 shows that, with a broken or defective plate 26 having beenremoved from the assembly of plates, leaving a gap, the replacementplate 31 with special end caps 32 is moved into position. The manifold16 can be spread apart to accommodate an annular collar 34 of the endcap 32, which has a greater width than the gap, i.e. wider than theportion of manifold that has been removed. The manifold sections arethen moved back into place, over the collars, with adhesive sealantapplied to permanently attach the collars to the manifolds. For an endcap/manifold structure with neck width about 7 mm, as above, the collar34 can have a width of about 19 mm.

It is also possible after removal of a membrane plate to simply repairthe break in the header 16 without replacing the defective membraneplate. Coupling sleeves such as shown in FIG. 9A rejoin the separatedsections of the header.

FIG. 7 shows the end caps 18 spaced only slightly apart, as close aspracticable for molding the structure, preferably by injection molding.As noted above, they could actually be connected, with no gap betweenthem, and a saw blade could be used to cut between end caps to extractthat section of the header pipe 14.

FIGS. 11 and 12 show a one piece external frame module 38, preferablyintegrally molded of plastic, that is configured to receive the assemblyor cassette of plates 12 with end caps/headers 14, such as shown inFIG. 1. As the drawing reveals, internal end walls 40 of the module 38preferably have series of vertically extending parallel grooves 42 intowhich outside ends 44 of the end caps 14 can slide, for a secure andsupportive fit with the module if added structure is needed for thatpurpose. FIG. 12 shows assemblies of plates contained in the modules,with four of the plate-carrying modules 38 arranged in stacked andside-by-side arrangement. Permeate from all of these sets of plates canbe carried away in pipes connected to the exit ducts 24. Suction isapplied to the membranes via these outlet ducts 24.

The above described preferred embodiments are intended to illustrate theprinciples of the invention, but not to limit its scope. Otherembodiments and variations to these preferred embodiments will beapparent to those skilled in the art and may be made without departingfrom the spirit and scope of the invention as defined in the followingclaims.

I claim:
 1. A membrane filtration system with a series of microfiltratonmembranes receiving liquid at outer surfaces to remove contaminants andcreate a permeate interior of the membranes, the permeate beingconducted away through pipes, the system comprising: the membranes beingceramic flat plate membranes positioned in side-by-side parallel planararrangement, the membrane plates being in a plate assembly whichincludes, at least at one end of the series of plates, an endcap/manifold structure of molded plastic material, having a generallyhorizontal header at an upper side and a series of vertically orientedend caps, each with a slot fitting closely over the end of a plate andbeing glued thereto, the end caps being in fluid communication with theheader so that the end caps receive permeate from the membranes toliquid connect the permeate from the plates into the header, and theplate assembly being without O-rings at end caps, whereby the membraneplates are retained in the assembly by the end cap/manifold structureand are connected securely and in fluid-tight relationship with the endcap/manifold structure without O-rings.
 2. The membrane filtrationsystem of claim 1, wherein the end cap/manifold structure is integrallymolded as one piece.
 3. The membrane filtration system of claim 1,further including replacement end cap sections for replacement ofdamaged plates, each of the replacement end cap sections having acoupling or collar to fit closely over the header pipe and having areplacement end cap integral with and extending down from the couplingor collar, the replacement end cap having a slot to fit closely over anend of a replacement membrane plate, whereby the header pipe in a plateassembly with a damaged plate can be ground out or cut through in twoplaces either side of an integral end cap of the assembly to remove thedamaged plate and a short section of header, after which a replacementplate having a replacement end cap section at one or both ends can beput into place with the coupling or collar of the replacement end capsection slipped over the header pipe and secured thereto by adhesive. 4.The membrane filtration system of claim 1, further including repaircouplings for the header to fit closely over the header, whereby theheader pipe in a plate assembly with a damaged plate can be ground outor cut through in two places either side of an integral end cap of theassembly to remove the damaged plate and a short section of header,after which a repair coupling can be put into place with the repaircoupling slipped over the header to join separated sections of theheader together, secured by adhesive.
 5. The membrane filtration systemof claim 1, wherein the membrane filtration system receives treatedwastewater in a wastewater treatment plant.
 6. In a wastewater treatmentsystem having a multiplicity of flat plate membranes connected to amanifold, a method for replacing an individual damaged membrane platewhile preserving remaining membrane plates in an assembly, comprising:providing an end cap/manifold structure integrally molded as one pieceand having a header pipe to which is connected a series of verticallyoriented end caps, each with a slot configured to fit closely over theend of a membrane plate, the end caps and header pipe being fluidlyconnected so that end caps can receive permeate from membranes to directthe permeate into the header, assembling a series of flat platemembranes in spaced parallel relationship to at least one endcap/manifold structures, at one end of the membrane plates with the endsof membrane plates inserted into the end cap slots, including applyingsealing adhesive to secure the membrane plate ends in the slots, to forma plate assembly, operating the plate assembly in a bath of liquid to befiltered, such that the liquid is drawn into micropores of the membraneplates and is channeled through the membrane plates into the end capsand ultimately into the header pipe, and carrying away the liquidpermeate with pipes connected to the header pipe, in the event ofdamage, breakage or failure of one of the membrane plates, removing ashort section of the header pipe so as to include the end cap that issecured to the damaged plate, to remove the damaged plate and section ofheader pipe between two separated sections of header pipe, thus leavinga gap in the header pipe where the damaged plate was located, replacingthe damaged plate by either (a) providing a replacement end cap sectionfor replacing the damaged plate and the removed section of header pipe,each of the replacement end cap sections having a coupling or collar tofit closely over the header pipe and having an end cap integral with andextending down from the coupling or collar and with a slot to fitclosely on an end of a replacement membrane plate, and attaching andadhering a replacement membrane plate to a replacement end cap sectionof the replacement membrane plate, and positioning the coupling orcollar of the end cap replacement section in the gap of the header pipesand, with adhesive applied, sliding the header pipe into the coupling orcollar at both sides of the coupling or collar, so as to patch theheader pipes and install the replacement membrane plate; or (b)providing a repair coupling that fits closely over the header pipe andrejoining separated sections of the header by slipping the coupling ontoboth of the separated sections with adhesive to seal the coupling to theheader pipe, without placing a new membrane in position of the damagedplate.
 7. The method of claim 6, wherein the step of removing a sectionof header pipe comprises using a jig and sawing out a section of headerpipe with an integral end cap bearing the damaged plate.
 8. The methodof claim 6, wherein the step of removing a section of header pipecomprises grinding or cutting out the section from a remaining portionof the header pipe.
 9. A set of parts for a membrane filtration systemwith a series of microfiltraton membranes receiving liquid at outersurfaces to remove contaminants and create a permeate interior of themembranes, the permeate being conducted away through pipes, comprising:the membranes being ceramic flat plate membranes positioned inside-by-side parallel planar arrangement, the membrane plates being in aplate assembly which includes, at least at one end of the series ofplates, a unitary end cap/manifold structure of molded plastic material,having a generally horizontal header at an upper side and a series ofvertically oriented end caps, each with a slot fitting closely over theend of a plate and being glued thereto, the end caps being in fluidcommunication with the header so that the end caps receive permeate fromthe membranes to feed the permeate into the header, and a plurality ofend cap replacement sections for replacement of damaged plates, each ofthe end cap replacement sections having a collar to fit closely over theheader pipe and having a replacement end cap integral with and extendingdown from the collar, the replacement end cap having a slot to fitclosely over an end of a replacement membrane plate, whereby the headerpipe in a plate assembly with a damaged plate can be ground out or cutthrough in two places either side of an integral end cap of the endcap/manifold structure to remove the damaged plate and a short sectionof header pipe at the end of the damaged plate, after which areplacement plate having a replacement end cap section can be put intoplace with the collars of the replacement end cap sections slipped overthe header pipe and secured thereto by adhesive.
 10. A set of parts asin claim 9, wherein the end cap/manifold structure is unitary,integrally molded as one piece.
 11. A set of parts as in claim 9,wherein the plate assembly includes two said end cap/manifoldstructures, one at each end of the series of plates.